That might sound ridiculous but I wonder if anyone have experience with custom furniture by small workshops in Finland or Estonia (near the coast)? i.e. they take design in SketchUp or CAD, give some advice, then proceed to make the actual furniture, mostly wood works with a little of metal or glass etc?

And what the price difference would be, compared to the IKEA type? like 20 fold or 5?

Custom furniture?

It depends a lot on what you want to have made.
I had a simple table custom-made in Finland. That was similar to a standard product the company made, I just wanted a different size. From what I remember the excess cost compared to the standard product was not large, and was in line with the size change.

On the other hand if you want a totally bespoke design this changes dramatically. I have seen figures more like 20-fold than 5-fold increase over Ikea-type products. This can change a bit if you intend to buy in bulk so the manufacturer can gear up for a production run, but it is still going to be an expensive option. I think that is understandable given the labour cost and increased skill level involved in a real custom work.

What do you want to have made? Is this a one-off, a small batch or production runs?

That might sound ridiculous but I wonder if anyone have experience with custom furniture by small workshops in Finland or Estonia (near the coast)? i.e. they take design in SketchUp or CAD, give some advice, then proceed to make the actual furniture, mostly wood works with a little of metal or glass etc?

And what the price difference would be, compared to the IKEA type? like 20 fold or 5?

Does the Ikea design/planning services not work for you? This is really cheaper than a real custom-made option by a small workshop.

one off yeah. My own conceptual designs (and need their advice on weight load and material etc). So around 20 fold? Any recommendation or names?

Search for "mittatilaus huonekalu" (made-to-measure furniture). Many of those are primarily carpenters, and may not produce their own metal and glass parts, but could know contacts where those could be sourced.